[Amps] 6 meter 8877 amplifier

[Mike Tubby]

Mike,

There is the Geoff Brown GJ4ICD design:

    http://www.gare.co.uk/gj4icd_8877_amplifier.htm

also on Chris' web site.

I built one of these about 12 years ago and it has given excellent service.

The only thing to watch with the 8877 on 6m is that all of the designs
that use a traditional pi tank (C-L-C) suffer from small tune-C and
latge load-C and getting the value of the inductor right can be
fiddly... at 50MHz we're near the edge of what can be done with the
pi-tank circuit taking in to account the anode capacitance of the 8877.

When you get your RF deck built its worth replacing the tube with a 2200
carbon resistor to ground (to simulate RL) and using a VNA make sure
your tuning/matching is in the right ball park before putting the tube
in and applying volts ;-)

I also have a 3-500Z QST 1971 design amp on 6m that uses the L-C output
with a shorted turn to tune the output - I have often wondered if this
arrangement would work better with the 8877 too.


Mike G8TIC



On 09/12/2012 17:06, mikflathead at aol.com wrote:
> I am  getting ready to start on a 8877 amplifier for 6 meters. Any good designs to copy or bad ones to avoid. Just curious before I start drilling. Thanks Mike
>